Hello everyone, my name is Nick, and I am the owner of Nick's TV repair. I am going to go over how to diagnose and fix your Vizio M470NV and M550NV TVs.
This thread should take care of 99% of all failures we see with these two models.
Experience:
We have helped fixed over 100 of these TVs in the past 6 months alone through our local and online repair services we offer on these models with a 97% success rate.
I will start by going over the extremely rare failures of this set first:
We have seen one M550NV experience a panel failure. The symptoms of a bad panel are going to be no picture on screen. We were able to diagnose this set by disconnecting one of the two ribbons between the T-con board and the panel. We disconnected one of the ribbons and turned the TV on, what we saw was a white screen on the disconnected side and a fully black screen on the other. We reconnected the ribbon and disconnected the other side. From there the disconnected side went from black to white, and the connected side was showing us proper picture. This meant that the side disconnected at the time was our faulty half which caused neither side to display on screen.
We have never seen in our shop these sets with bad LED's, bad LED driver board, bad power supply board, or a bad T-con board. However it is not impossible as there is a thread on bad caps with a one of these sets experiencing bad LEDs. It is extremely rare but can happen.
Now to the 99% of failures we see with these models are going to be main board failures listed below
Symptoms of a bad main board:
Our first symptom is usually due to both a faulty Silicon Image chip with location number U41 and additionally a faulty transistor at location Q29. U41 is the larger IC close the the bottom HDMI ports and Ethernet port. You can check the chip by looking at the capacitors near/around it for shorts. If you find shorted capacitors, it is due to this chip malfunctioning. The Q29 transistor is located about 2 millimeters off to the right of the large heatsink. It is a very small three legged surface mount component. While in circuit, it should show around 10k ohm and slowly rising with the negative lead on the bottom leg and positive lead on the top left leg. With the negative lead still on the bottom leg and the positive lead on the top right leg you should be seeing around 29k-32k ohms. If you do have a shorted silicon image chip U41 but still good readings on your Q29 surface mount transistor, we still would advise replacing that transistor as well since hey tend to fail together.
Our second and third symptoms are due to a faulty Nand chip with location number U6. This will be the rectangular chip located under the heat sink. BE VERY CAREFUL WHEN REMOVING THE HEAT-SINK!!! The heat-sink has adhesive on it that is stuck to a smaller heat-sink which makes contact with the CPU chip. If improperly removed, the BGA chip can get ripped off the board and cause your board to be beyond economic repair. What we do is use hot air on the top of the heat-sink at around 300 degrees for around 20 to 25 seconds to loosen up the adhesive. This will make it easier to remove and will help prevent ripping traces on the CPU chip. (You must de-solder the large heatsink from the bottom as well) To find a replacement with proper software on this, you can purchase a chip on ebay from Coppell TV repair. (We do not sell these as repair kits as these failures very rarely occur)
Our 4th through 8th symptoms are all due to bad contact between the main CPU chip and the main board.
These CPU chips also called BGA which stands for Ball Grid Array run fairly hot. The chips themselves are very resistant and almost never fail, however after years of heating and cooling due to the Tv being turned on and off, microscopic cracks will form in the solder balls between the chip and the board. These cracks, will prevent data from going through and thus malfunctions will occur in many different ways dependent on which solder connections break first. There are two ways to fix this problem, a correct way, and an incorrect way. The incorrect way also the easier way would be to perform a reflow on the chip. What that means is to apply heat with the use of either an Infrared heating element or an oven. What a reflow means is you are heating up the solder balls to their melting point. As the solder balls heat up, they will expand and reconnect the cracked solder joints as they melt back together. The problem with this, is that they will almost never reconnect properly. This will only temporarily fix your issue and a repeat failure will come either within a few weeks or a few months.
What we have done at NicksTvs to properly fix these boards, is fully remove the chip from the board followed by cleaning up all the old solder from both the board and from the chip. From there we rework the chip by replacing all the old solder balls with new ones using softer, more malleable solder which is less prone to cracking in the future. I would not recommend performing this task unless you have access to a BGA rework station and experience using one. This is a very time consuming and delicate procedure. Once the BGA chip has been reworked, we tin the board, add a thin coat of special flux and reattach the chip. This repair procedure allows for extended life time on the board. This is why we are one of the only companies able to provide you with a full year warranty on these repairs. You will notice most repair centers only off 30-60 days and sometimes up to 90 days warranty on their repairs. This is because they only reflow the chip.
I hope this post/thread has helped people understand what goes on with these board and to avoid buying some of the advertised repair kits which contain in my opinion randomly selected components. Yes Zemtronix I am talking about you.
I have set this thread to email me every time someone writes a comment, so if you have further questions, please feel free to post and I will try my best to answer questions.
This thread should take care of 99% of all failures we see with these two models.
Experience:
We have helped fixed over 100 of these TVs in the past 6 months alone through our local and online repair services we offer on these models with a 97% success rate.
I will start by going over the extremely rare failures of this set first:
We have seen one M550NV experience a panel failure. The symptoms of a bad panel are going to be no picture on screen. We were able to diagnose this set by disconnecting one of the two ribbons between the T-con board and the panel. We disconnected one of the ribbons and turned the TV on, what we saw was a white screen on the disconnected side and a fully black screen on the other. We reconnected the ribbon and disconnected the other side. From there the disconnected side went from black to white, and the connected side was showing us proper picture. This meant that the side disconnected at the time was our faulty half which caused neither side to display on screen.
We have never seen in our shop these sets with bad LED's, bad LED driver board, bad power supply board, or a bad T-con board. However it is not impossible as there is a thread on bad caps with a one of these sets experiencing bad LEDs. It is extremely rare but can happen.
Now to the 99% of failures we see with these models are going to be main board failures listed below
Symptoms of a bad main board:
- TV turns on, but the on screen vizio logo freezes and the tv eventually cycles off and back on again. (this can sometimes happen endlessly or until power plug is removed)
- TV turns on, both sound and picture come through, however the TV menu is very slow to navigate and seems to freeze a lot.
- TV turns on, the menus and component/coaxial input work, however the HDMI ports don't appear as optional inputs
- TV turns on, menus work smart apps work, but the HDMI ports have no sound and no picture. (No signal keeps appearing)
- TV turns on and HDMI ports work, but no sound
- TV does not turn on, and the small vizio logo at the bottom of the frame keeps flashing white to orange endlessly
- Tv does not seem to turn on, the vizio logo on frame does not flash but stays orange.
- Tv logo goes from orange to white but the TV does not turn on.
Our first symptom is usually due to both a faulty Silicon Image chip with location number U41 and additionally a faulty transistor at location Q29. U41 is the larger IC close the the bottom HDMI ports and Ethernet port. You can check the chip by looking at the capacitors near/around it for shorts. If you find shorted capacitors, it is due to this chip malfunctioning. The Q29 transistor is located about 2 millimeters off to the right of the large heatsink. It is a very small three legged surface mount component. While in circuit, it should show around 10k ohm and slowly rising with the negative lead on the bottom leg and positive lead on the top left leg. With the negative lead still on the bottom leg and the positive lead on the top right leg you should be seeing around 29k-32k ohms. If you do have a shorted silicon image chip U41 but still good readings on your Q29 surface mount transistor, we still would advise replacing that transistor as well since hey tend to fail together.
Our second and third symptoms are due to a faulty Nand chip with location number U6. This will be the rectangular chip located under the heat sink. BE VERY CAREFUL WHEN REMOVING THE HEAT-SINK!!! The heat-sink has adhesive on it that is stuck to a smaller heat-sink which makes contact with the CPU chip. If improperly removed, the BGA chip can get ripped off the board and cause your board to be beyond economic repair. What we do is use hot air on the top of the heat-sink at around 300 degrees for around 20 to 25 seconds to loosen up the adhesive. This will make it easier to remove and will help prevent ripping traces on the CPU chip. (You must de-solder the large heatsink from the bottom as well) To find a replacement with proper software on this, you can purchase a chip on ebay from Coppell TV repair. (We do not sell these as repair kits as these failures very rarely occur)
Our 4th through 8th symptoms are all due to bad contact between the main CPU chip and the main board.
These CPU chips also called BGA which stands for Ball Grid Array run fairly hot. The chips themselves are very resistant and almost never fail, however after years of heating and cooling due to the Tv being turned on and off, microscopic cracks will form in the solder balls between the chip and the board. These cracks, will prevent data from going through and thus malfunctions will occur in many different ways dependent on which solder connections break first. There are two ways to fix this problem, a correct way, and an incorrect way. The incorrect way also the easier way would be to perform a reflow on the chip. What that means is to apply heat with the use of either an Infrared heating element or an oven. What a reflow means is you are heating up the solder balls to their melting point. As the solder balls heat up, they will expand and reconnect the cracked solder joints as they melt back together. The problem with this, is that they will almost never reconnect properly. This will only temporarily fix your issue and a repeat failure will come either within a few weeks or a few months.
What we have done at NicksTvs to properly fix these boards, is fully remove the chip from the board followed by cleaning up all the old solder from both the board and from the chip. From there we rework the chip by replacing all the old solder balls with new ones using softer, more malleable solder which is less prone to cracking in the future. I would not recommend performing this task unless you have access to a BGA rework station and experience using one. This is a very time consuming and delicate procedure. Once the BGA chip has been reworked, we tin the board, add a thin coat of special flux and reattach the chip. This repair procedure allows for extended life time on the board. This is why we are one of the only companies able to provide you with a full year warranty on these repairs. You will notice most repair centers only off 30-60 days and sometimes up to 90 days warranty on their repairs. This is because they only reflow the chip.
I hope this post/thread has helped people understand what goes on with these board and to avoid buying some of the advertised repair kits which contain in my opinion randomly selected components. Yes Zemtronix I am talking about you.
I have set this thread to email me every time someone writes a comment, so if you have further questions, please feel free to post and I will try my best to answer questions.
Comment